UCSF's Boxer Comments on Promising Alzheimer's Vaccine Study
A recent Japanese study, published in the Proceedings of the National Academy of Sciences, found that a potential DNA vaccine for Alzheimer's disease cut levels of amyloid proteins in the brain. Scientists believe that these amyloid proteins, noted for their clumping into plaques, trigger symptoms associated with the disease.
While acknowledging that a vaccine is promising technology for preventing or treating Alzheimer's, UCSF neurologist Adam Boxer, MD, PhD, believes it is too early to tell whether what seems to work in mice can do the same safely in humans.
Nor, adds Boxer, is it clear how this new vaccine compares to more conventional vaccines that are already available.
What the Japanese scientists did: The Japanese technique used DNA that codes for amyloid proteins. The DNA, rendered incapable of replicating itself, was injected into the mice, where it produced a gentle immune response. This immune system response reduced the level of amyloid proteins by up to 50 percent in some parts of the brain.
Why this is an advance: In previous vaccine studies, some in humans, an amyloid protein vaccine caused the body to generate antibodies to amyloid. This made the brain swell. This Japanese approach produced no such side effects.
What Boxer believes about more conventional Alzheimer's disease (AD) vaccines: More conventional AD vaccines have been made using the same technologies that are used to make vaccines against infectious diseases such as the flu. With conventional vaccines, the antigen (e.g., flu virus) that the vaccine is directed against is recognized by the body's immune system, usually by making small proteins called antibodies. These antibodies stick to the antigen and help the immune system to clear it before it does damage. Conventional Alzheimer's vaccines have used a protein, called beta-amyloid, which builds up in people's brains and causes damage, as the antigen. Because of concerns about toxicity from an older Alzheimer's vaccine that was tried in humans (see above), some of the newer approaches use purified anti-amyloid antibodies, like those that would be generated from a vaccine, to clear toxic amyloid from the brain.
What is happening on the vaccine front at UCSF: The Alzheimer's vaccine study at UCSF uses a purified antibody that sticks to the toxic beta-amyloid protein (that causes brain damage) in order to clear the amyloid from the body and, it is hoped, prevent some of the brain damage. Patients receive the antibody as an intravenous infusion every three months and are followed for changes in their memory, day-to-day function and the appearance of their brain on MRI scans. UCSF researchers hope to enroll more patients in the study in the next few months.